The invention relates to a method and apparatus for the in line sampling of chemicals which undergo a chemical reaction in line.
When chemical production is carried out on an industrial scale, the chemical reactions leading to a chemical product are often carried out while the chemicals which undergo the reaction are pushed through pipes or lines in the industrial plant, at a temperature conducive to the chemical reaction, in the presence of the necessary catalysts. In order to maximize the yield, and to ensure that the correct product is produced (in complex organic chemical reactions there is often a number of possible products which can be produced given the same starting materials, the products depending on the reaction conditions).
For purposes of illustration, reference is made to the production of polymer cement samples, wherein precursor polymer materials are pushed through a polymerization reactor in a solvent solution, usually a hydrocarbon solvent solution. For the purposes of quality control, it is desirable to check the progress of the chemical reaction at certain points in the line in order to make sure that the proper precursors are being formed at the proper stage of the reaction. This can be done by taking a sample of the reaction mixture, quenching (i.e., stopping the chemical reaction so that the chemical makeup of the materials sampled does not change before an analysis can be made), and analyzing the chemicals present at the point in time that the sample is taken out of the reaction line.
Since such a sample is captured at reaction conditions, the chemicals of interest are usually at elevated temperatures and are surrounded by volatile hydrocarbons and other volatile organic compounds. Chemicals at high temperatures, and exposure to volatile hydrocarbons raise safety issues for the laboratory operator, or any technician that is charged with collecting individual samples.
Prior to the present invention, a procedure used to obtain such samples was to take a sample of the reaction materials, and to dump it into a jar containing a shortstop chemical (i.e. a chemical used to stop the chemical reaction). In some embodiments, the jar used to collect the reaction materials was lined with a chemical resistant plastic, and the shortstop chemical was mixed with the reaction chemicals in the plastic material lining the sample collection jar.
U.S. Pat. No. 4,651,574 teaches a delivery system for testing a sample that includes a cooler. The sampling system described by the patent, however, is not adequate for testing rubber and plastics polymerization processes.
It is an object of the present invention to provide a sampler that reduces or eliminates the laboratory technicians exposure to volatile hydrocarbon, and exposure to the reaction chemicals themselves. Other objects of the invention will be apparent from the following description and claims.
An apparatus for sampling in-line chemicals comprises (a) a conduit leading from a chemical reaction line to a sample holder, (b) a cooling means associated with the conduit, (c) a sample holder connected to the conduit, the sample holder comprising a container having two opposed ends and removable covers associated with each end, (d) a chemical agent contained within the sample holder, the chemical agent being adapted to interrupt a chemical reaction carried out in the chemical reaction line, and (e) means for mixing the chemical agent with chemicals from the chemical reaction line.
In the illustrated embodiment, the cooling means is a cooling coil and the conduit leading from the chemical reaction is contained within the tubing of the cooling coil.
The apparatus may further include a vacuum for exhausting volatile solvents and chemicals from a sample.
The sample holder may be made from a transparent material, and the apparatus may further include a sample holder receiver adapted to fit over the sample holder and to hold a valve for controlling inflow of a sample into the sample holder. The valve preferably contains an eductor removing volatile solvents and chemicals from around the sample.
In the illustrated embodiment, the mixing means is a chemical resistant liner contained within the sample holder, which is used for containing the shortstop chemical agent and receiving chemicals from the chemical reaction line, whereby the shortstop chemical agent is mixed with the reaction chemicals by kneading the chemical resistant liner.
In the illustrated embodiment, the sample holder is a cylinder having two opposed threaded ends, and threaded covers are associated with each threaded end. One threaded cover is fitted with a septum for receiving a needle for delivering the sample. And the liner is a chemically resistant, flexible plastic material.
In the illustrated embodiment, the means for cooling the sample is a cooling coil comprising tubing associated with the conduit, whereby the conduit is contained within the tubing.
Also provided is a method for sampling in-line chemicals comprising the steps of (a) inserting a valve into a chemical reaction line, (b) drawing a sample from the chemical reaction line while a chemical reaction is in progress, (c) connecting a sample holder to the conduit, the sample holder comprising a container having two opposed ends and removable covers associated with each end, (d) tansporting the sample through cooling means for reducing the temperature of the sample delivered to the holder, and (e) mixing the sample with a shortstop chemical agent adapted to stop the chemical reaction.
The method may include the further step of evacuating volatile solvents and chemicals from around the sample in the sample holder and providing an evacuated box for storing the sample. The sample holder may be provided in the form of a cylinder which is threaded on both ends and having a threaded cover associated with each end. The cylinder may contain a chemical resistant liner, and a shortstop chemical agent contained within the liner.
The method may be carried out by removing the bottom cover from the cylinder, and mixing the sample with the shortstop chemical agent by kneading the liner.